Laminated spinneret



Sept. 7, 1965 T. E. CROMPTON LAMINATED SPINNERET 2 Sheets-Sheet 1 Filed Dec. 27, 1962 FIG.|

INVENTOR. T. E. CROMPTON MQ 41mm J ATTORNg Sept. 7, 1965 T. E. CROMPTON LAMINATED SPINNERET 2 Sheets-Sheet 2 Filed Dec. 27, 1962 INVENTOR. T.E. CROMPTON MA WM ATTORNEY United States Patent 3,204,290 LAMINATED SPINNERET Thomas E. Crompton, Cary, N.C., assignor to Monsanto Company, a corporation of Delaware Filed Dec. 27, 1962, Ser. No. 247,613 3 Claims. (Cl. 18-8) This invention relates to an apparatus for producing artificial filaments and more particularly to an improved spinneret for producing filaments of diversiformed crosssectional configuration, which filaments may be either conjugated or non-conjugated.

According to one aspect of the present invention, the comparatively recent advent of filaments exhibiting diversiformed cross sectional configurations as, for example, those commonly referred to as multi-lobal filaments, has served to reemphasize the desirability of new approach in the design of spinning apparatus employed in the production of such filaments. The significance of these filaments of varying configuration lies in the discovery that they have, for example, improved bulk, resilience and covering power due to the increased susceptibility of such filaments to crimping and similar post-treatments, as well as a degree of opaqueness unattainable in filaments of a circular or near-round crosssection, which serves to minimize apparent soilage during wear to thereby impart a longer lasting brightness and freshness to the article made from such filaments.

In accordance with another aspect of the present invention, two or more filament-forming materials of different properties in a fused or plasticized state or in the form of solutions thereof, are extruded in separate or only partially intermingled phases through a common orifice or a plurality thereof, whereupon they are joined together in an eccentric or side-by-side relation upon exposure to a setting medium which may be gaseous or liquid, functioning either by cooling, precipitating, or evaporative eifect, to form unitary filaments each of which is a composite of diiferent materials forming discrete portions of the body of the filament.

Any of the filament-forming materials or solutions may be utilized, including viscoses, proteins, such as caseins and soybean proteins, cellulose derivates, such as cellulose acetate and ethyl cellulose and resins, such as nylons, the vinyl resins, especially the copolymers of vinylchloride and vinylacetate, and the vinylidene halides. When different cellulose xanthates or viscoses are used they may differ as to either age, cellulose content, sodium hydroxide content, or carbondisulphide content and as to the type of cellulose from which they are made, such as wood pulp or cotton pulp, or as to any two or more of these factors. Where other cellulose derivatives Such as the esters or ethers are used, they or their solutions may differ as to viscosity, cellulose content, or as to degree of polymerization or substitution of the cellulose change therein. Where resin solutions are used, the solutions may differ as the kind of resin, viscosity and the degree of polymerization of the resin. Two spinning materials of different classes may be combined, such as a protein with a viscose, a protein with a cellulose acetate, or a cellulose acetate with a vinyl resin. It is only necessary that the materials in the form employed, whether fused or in solution, do not 3,2042% Patented Sept. 7, 1965 "ice mutually precipitate one another and that they adhere together in the final filaments.

The filaments may be extruded into either a liquid or a gaseous setting, or precipitating medium, depending upon the solutions that are used. For instance, viscose solutions may be extruded into an acid-precipitating bath and other cellulose derivatives and resins, or their solutions, may be extruded into either a liquid or a gaseous medium.

When it is desired to produce crimpy filaments, the filaments, shortly after extrusion, are stretched and are immediately thereafter permitted to relax; or, after formation of the filaments, they are plasticized, such as by wetting, in a relaxed condition in order to effect shrinkage. Again, completely set filaments, whether stretched or not during formation, may be subsequently stretched, plasticized and relaxed to effect shrinkage and consequent crimping. Various forms of apparatus may be used for stretching the filaments, as for example, by passing them about positively driven rollers, wherein succeeding rollers are driven at succeedingly higher speeds. Alternatively, a thread-storing, thread-advancing device about which the filaments continuously travel in a helical path, the individual convolutions of which become progressively larger, may as well be employed. The stretching procedure orients the micelles or molecules of the several component materials making up each of the filaments to different degrees and, where it is preformed as an after-stretching procedure, it is carried to such an extent that at least one and preferably all components of the filament are stretched beyond the elastic limit so that the filament is in a condition of unbalanced stresses across its cross-section. When relaxed and subjected to a shrinking process, the several components of the filaments will shrink or contract to different degrees, with the result that the filament will have an appreciable crimp which is generally such that the filament takes the form of a regular or irregular helical coil which may reverse itself in direction at more or less frequent intervals of regular or irregular occurrence, and such that the eccentric components of a filament follow a helical path about the longitudinal axis of the filament, which path may reverse itself at more or less frequent, irregular intervals. The component materials under the greater shrinkage during the crimp formation or having the greater elastic recovery after stretching generally have been found to form the inner portions of the filaments at the bends of the crimp therein.

The individual crimped filaments produced by the apparatus of this invention in their state of normalcy are characterized by a stabilized condition having an inherent distortion which makes the crimp one of a permanently recoverable character. The filaments, whether crimped or not are of a unitary structure having a cross-section at all points of the filament length which comprises two or more substantially distinct areas, each of which has a different composition than that of the others and at least one of which is eccentrically disposed with respect to the filament cross-section. At least two of the component areas are composed of materials having distinct differences in properties especially those properties which give rise to differences in shrinkage in response to those influences which can effect shinkage or an elastic recovery from a stretched condition.

Where it is desired to incorporate the separate characteristics of two individual polymeric species into one filamentary structure, it is frequently advantageous to spin the two polymeric species in such a Way that each species remains separate :and distinct Within a different area of the fiber cross-section. This is particularly true Where the difference in properties of the two species are such as to produce a crimped fiber when the two species are spun in eccentric relationship to each other. For example, when two polymeric species having different shrinkage characteristics appear in eccentric relationship to each other in a single fiber, that fiber Will develop a desirable spiral-type crimp when it is treated under conditions which cause the two components to shrink.

Various embodiments of spinning apparatus for producing filaments of diversiformed cross-sectional configuration, with or without composite or side-by-side components from two separate solutions or melts which are capable of forming fibers on evaporation, coagulation, or cooling which will produce the desired results, are presently available. It is, however, a comm-on objection to such spinneret devices that they are prohibitively intricate in design and, concomitantly, costly in manufacture. The high cost is largely a result of the necessity of an abundance of minute and precisely configured passages necessitating precision drilling and milling operations, the requirements of which vary greatly between the individual spinneret designs. Also, a separate spinneret must be designed for each different filament configuration it is desired to produce. A spinneret device capable of producing filaments of diversiformedcross-section, with or without multi-component conjugation, which would simplify fabrication techniques and require less precise machining operations with no sacrifice in end roduct quality is definitely indicated.

It is, therefore, an object of the present invention to provide a novel spinneret construction susceptible to heretofore unrealized economies in fabrication without sacrificing the quality of the end product.- A further object of this invention is a high precision spinneret readily adaptable to mass-production techniques which may be utilized to produce either conjugated or non-conjugated filaments of diversiformed cross-sectional configurations. Still another object of the invention is to provide a spinneret of laminated construction whichis susceptible to rapid interchange of its component parts toallow a wide range of choice in the cross-sectional configurations of the spinning orifices defined thereby.

A better understanding of the present invention may be had by a reference to the appended drawings, which are merely illustrative of some of the possible embodiments thereof and in which:

FIG. 1 is a partially sectionalized, assembled view of a typical spinneret of this invention; 1

FIG. 2 is an exploded view of the spinneret shown in FIG. 1;

FIG. 3 is a highly enlarged, fragmentary view of illustra'tive configurations of composite spinneret orifices obtainable by the construction of this invention;

FIG. 4 is a full-face view of an alternative form of orifice plate designed specifically for use in non-conjugate spinning operations, and

FIG. 5 is a view similar to that of FIG. 4 showing the details of another possible embodiment of the orifice plates.

According to the present invention, the foregoing and other objects are attained by providing a spinneret design of laminated construction, the component parts of which are of extremely simplified design, making possible considerable savings in the cost of fabrication and ease of operation without sacrifice in the quality of the end product. The concept comprehends the use of relatively thin, inexpensive plate stock in which there is formed by stamping, machining, chemical etching, ultrasonic abrasion, or other suitable techniques of metal fabrication, voids, re-

cesses and depressions of novel alignment and configuration, which plates when clamped together in operative fashion, result in a spinneret assembly having intricately configured passageways and defining spinneret orifices of variable, diversiformed cross-sectional configurations capable of rapid and precise variation, which spinneret is capable of extruding variously conjugated and non-conjugated multi-lobal filaments. Heretofore, such passage and orifice configurations have been effected in the prior art spinnerets by intricate and costly machining operations on relatively massive component parts, whichspinnerets are incapable of being varied to produce other and different filament cross-sections.

Referring now in detail to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1, there is shown an assembled spinneret 10 made in accordance with the concepts of this invention with portions cut away for greater clarity. Spinneret 10 is seen to basically comprise a series of plates stacked in laminated or sandwich-like fashion and clamped between feed blocks 12, 14 by means of stud bolts 16 and nuts 18, the view of the assembled spinneret in FIG. 1 being of its orifice face to show one possible arrangement of the composite spinneret orifices 20. For a clearer understanding of the interrelationship between the variously configured plates and feeder blocks, the reader is referred to the showings of FIGS. 2 and 3.

As shown in FIG. 2, the double-feed block 12, in cooperation with the single-feed block 14, performs two vital functions in the operation of the instant spinneret assembly. One such function is that, by virtue of their mass, rigidity and the precise flatness of their inner faces, these feed blocks serve to compress the intervening orifice and spacer plates into highly conformed parallel planes to assure more perfect alignment of the various voids and component orifice slots and to minimize the possibility of inter-plate leakage. Another function of these blocks is to serve as distribution manifolds between lines supplying spinnable mediums to the spinneret assembly and the various passageways defined therein by the orifice and spacer plates when such plates are stacked in face-to-face relationship in the manner illustrated. The rectangular outline of feed blocks 12, 14 and the orifice and spacer plates 36, 48, respectively, is not critical, although it has been found convenient in machining operations. The double-feed block 12 is provided with an integral, upstanding collar 22 having formed therein an internally threaded bore 24 for reception of a supply line, not shown, through which is conveyed the desired spinnable medium. Communicating with this internal bore is a manifold passage 26 having branched portions 28, 30, these branched portions being so shaped as to be in alignment with selected portions of the voids or passageways formed in the spacer and orifice plates 36, 38, as will later be more fully explained. Laterally disposed relative to each of these branched portions, there are provided relatively large holes 32 for reception of stud bolts 16. The singlefeed block 14 has a similar configuration to that of the double-feed block 12, save that, in lieu of the branched portions 28, 30, there is provided a single supply port of a size and alignment identical to that of manifold passage 26. In the particular embodiment illustrated, the single supply port of feed block 14 will align with the central distribution aperture 33 formed substantially centrally of each spacer plate 38 and the upper extremities of the inner branches 34 of the bifurcated feeder passages 35 which are formed in each of the orifice plates 36. It should here be noted that, though feed blocks 12, 14 have been described and illustrated as disposed at either end of a stacked series of orifice and spacer plates arranged in the desired sequence, such feed blocks, with minor modification, may be placed at a point intermediate the ends of a series of orifice and spacer plates, wherein each feed block would feed separate sequences of plates located adjacent its obverse faces. Of course, where such a modification is resorted to, relatively massive end blocks would take the positions of the feed blocks illustrated in FIG. 2 to effect proper clamping and alignment of the intervening feed blocks and the spacer and orifice plates. The provision of such intermediate feed blocks has been found quite helpful where pressure distribution problems are encountered by virtue of the fact that the flow path of a spinnable medium between the feed block and the spinneret orifice most remote therefrom is substantially reduced to thereby provide greater uniformity in pressure distribution at the various spinneret orifices which in turn promotes greater uniformity in the filaments extruded therefrom.

Turning now to the details of the orifice plates 36, a typical embodiment of which is illustrated in FIG. 2, such plates are seen to be of an outline similar to that of the feed blocks 12, 14 and have similarly located holes 32 so spaced as to be precisely alignable with similarly numbered holes in the feed blocks. The particular orifice plates illustrated in FIG. 2 are seen to comprise a bifurcated, substantially Y-shaped void, the lower portion of which terminates in a component spinneret orifice or slot 40 which communicates with a peripheral edge of orifice plate 36. The particular configurationof the inner and outer feeder branches 34, 42, respectively, is significant only to the extent that they should be so dimensioned as to provide as nearly a uniform pressure distribution at the various orifice slots as is possible. In general, this will dictate that the feeder branches 34, 42 decrease in cross-sectional area as they approach the slot 40 where these branches juncture. Preferably, the juncture of the two feeder branches 34, 42 should be a gently merging one rather than abrupt in order to promote laminar merging and minimal intermixing of the spinnable or mediums conveyed thereto.

The spacer or partition plates 38, an illustrative embodiment of which is best view in FIG. 2, are each seen to be provided with a series of uniformly spaced distribution apertures, viz. a central distribution aperture 33 and, in this example, a pair of outer distribution apertures 44 disposed laterally of the central distribution aperture. These distribution apertures are so located as to be capable of precise alignment with the upper extremities of the bifurcated feeder passage 35 and a similar distribution aperture 46 provided in each of the orifice plates 36. At each of the lateral extremities of spacer plate 38, there is provided a hole 32 of the same size and alignment as similarly numbered holes in the feeder blocks 12, 14 and the orifice plate 36.

As will be noted from an inspection of FIG. 2, the width of the component spinneret orifices or slots 40 may be varied from plate to plate and slots of the same or dissimilar width may be laterally off set whereby, upon stacking a selected sequence of orifice plate, widely varying configurations of composites spinnerets orifices 20 may be readily obtained, some possible configurations being shown in the highly enlarged, fragmentary view of FIG. 3 depicting a portion of the spinning face of the spinneret 10. As there indicated, innumerable variations in the cross-sectional configuration of the composite orifice 20 may rapidly be efiected simply by a proper choice of alignment and width of the component spinneret orifices 40. By way of example and not by limitation, FIG. 2 depicts a spinneret composed of a series of three orifice plates bounded on either side by spacer plates followed by a second series of three orifice plates, and so on, until a spinneret of the desired dimension containing the desired number of composite spinneret orifices is obtained. In the particular example of FIG. 2, the mid-plate of each series of three orifice plates 36 defines a component orifice slot 40 of a width greater than the component orifice slots of adjacent orifice plates, all three component orifices being aligned about a common center to define a composite orifice slot 20 of cruciform cross-sectional configuration as depicted by the composite orifice appearing upper-leftmost in FIG. 3. Obviously, any number of orifice plates may be employed in constructing a composite orifice of the desired configuration, the only limitation in the practice of the invention being the use of at least two or more orifice plates in contiguous, face-to-face relationship. It should be noted that in normal practice a spinneret having composite orifices of uniform cross-sectional configuration will be employed rather than the range of configurations depicted in FIG. 3.

Assembly of the spinneret comprising my invention is quite simple, involving nothing more than the stack ing of the spacer and orifice plates in a sequence that will afford the desired composite orifice configuration, which sequence of plates are bounded at either end by feed block 12, 14 or optionally, by blank end blocks where the previously described intermediate feeder blocks are employed. Any desired number of identical or varying sequences or orifice plates may be employed, subject to the limitations of pressured distribution. As is clear from an inspection of the drawings, when the various plates and blocks are clamped together in their operative interrelationship, there results a particular alignment of the various Voids and passageways formed in the component parts thereof to define a spinneret assembly having composite orifices of the desired crosssectional configuration, wherein each of such orifices is supplied by two discrete systems of passageways.

Considering the alignment of the particular plate configurations illustrated in FIG. 2, it will be seen that, upon placing an orifice plate 36 in face-to-face relationship with a spacer plate 38, the upper extremities of the bifurcated feeder passage 35 will align with one or the other of the two outer distribution apertures 44 and the central distribution aperture 33, the remaining outer distribution aperture 44 aligning with the orifice plate distribution aperture 46. By placing the second orifice plate having a bifurcated feeder passage of an alignment identical to that of the first mentioned orifice plate, followed by a second spacer plate, there will be defined a composite spinneret orifice 20. In the particular configuration illustrated in FIG. 2, the spinnable medium supplied to the single-feed block 14 is conveyed to the central distribution aperture 33 of spacer plate 38, which aperture communicates with each of the inner feeder branches 34 of the bifurcated feeder passages 35 throughout the length of the assembled spinneret. The spinnable medium supplied to the double-feed block 12, which may be the same medium as that supplied by the single feed block 14, or a different medium if a conjugated filament is desired, is conveyed to the two branch portions 28, 30 of manifold passage 26 as viewed in FIG. 2, the branch portion 28 communicating with the upper extremities of the left most outer feeder branch 42 and branch portion 30 of the manifold passage 26 communicating with the orifice plate. distribution aperture 46 to pass therethrouigh, thence through outer distribution aperture 44 of spacer plates 38 to the next series of orifice plates, the bifurcated feeder passage 35 of the latter series being of such orientation as to be in partial alignment with distribution aperture 46.

It should be mentioned that the use of the spacer or partition plates 38 is considered to be optional in that their primary function is to effect sufiicient spacing between composite spinneret orifices 20 to insure against the possibility of fusion of the filaments while still in plasticized condition as they are extruded from such orifices. For example, in an arrangement where the combination of the thickness of the orifice plate 36 and the distance measured in the plane of the plates between the composite orifice slots 20 are suflicient, in and of themselves, to insure against the possibilities of such fusion, the spacer plates may be omitted and the various 7, sequences of orifice plates of alternating orientation may be placed in direct contact. Also, the configuration of the bifurcated feeder passages 35 is not considered a critical part of this invention, the only requirement being that they be of such configuration as to align with the distribution apertures of adjacent spacer plates, the distribution aperture 46 and bifurcated feeder passage 35 of adjacent orifice plates to communicate between such apertures and the component orifices 20. It is likewise possible that a given component orifice 40 may be supplied by more than two feeder passages, whereby a third spinnable medium may be supplied thereto. The thickness of the orifice plates and the width of the various component orifice slots 40 are not critical to the present invention and may be varied over a wide range, depending on the filament type, whether it is conjugated or not, and upon its denier and cross-sectional configuration. For example, it has been found that suitable results may be obtained with orifice plates varying in thickness from 0.03 of an inch to 0.1 of an inch. By varying the thickness of the orifice plate, with a consequent variation of the cross-sectional configurae tion of the component orifice slots 40, by varying the width and alignment of adjacent component orifice slots, and by varying the relative pressures at which the spinnable mediums are supplied to the bifurcated feeder passages 35, fibers having widely varying cross-sectional configurations and physical characteristics'may be obtained, as will be appreciated by those skilled in the art of filamentary spinning.

Reference will now be had to another of the many possible variations in the configurations of the voids and passageways and the numbers of orifice slots formed in the various plates, as contemplated by my invention. Referring to FIG. 5, it is seen that one such embodiment may comprise an orifice plate 36 on either face of which is formed, by chemical etching or other suitable process, a continuous, wave-like depression or recess, the crests of such wave-like depression registering with the distribution apertures 33, 44 of the optional spacer plates 38 when such orifice and spacer plates are placed in face-to-face contact with holes 32 in precise alignment. Alternatively, similarly shaped passageways may be defined by employing a segmented orifice plate, the members of which are affixed by any suitable means such as by spot-welding or dowelling, to the face of a spacer plate 38. In either case the bottom region of such wave-like depression or passageway is formed to communicate with a peripheral edge of the orifice plate by way of a component orifice slot 40 to thereby define a component spinneret orifice. To provide for lateral offset of adjacent series of orifice plates, which offset is evident in the two sequences of orifice plates shown in the spinneret of FIG. 2, the wave-like depression or passageways is located oif-center with respect to the center distance between holes 32 of each orifice plate by a distance X/2, which is equal to one-half the center line distance between the apexes of the wave-like passageway. By this arrangement, orifice ofiset may be effected simply by placing the opposite faces of two identical plates or series of plates toward each other, which plates may optionally be intervened by a spacer plate.

It will be appreciated that by stacking a desired number of orifice plates in sequences of two or more in a manner to align holes 32, there will be formed .a laminated spinneret having a plurality of parallel rows of composite spinneret orifices 20, each component orifice comprising two or more component spinneret orifices 40, each of which is fed by at least two theretofore discrete systems of passages, as defined by the particular alignment of voids formed in the component parts of the spinneret. By supplying a different spinnable medium to each of feed blocks 12, 14, a conjugated filament of virtually any desired cross-sectional configuration may be extruded from each of the individual composite slots 40. Of course, a non-conjugated filament may be extruded merely by supplying the feed blocks with the identical spinnable medium. Further dilferences in the cross-sectional characteristics of the components of a conjugated or non-conjugated filament may be obtained by the expedient of varying the pressures at which the different spinnable mediums are supplied to the separate and discrete passageways.

Reference will now be had to another, simplified embodiment of my invention which is designed to produce non-conjugated filaments of diversiformed cross-sectional configuration, this embodiment differing from those depicted in FIGS. 2 and 5 only in the details of the orifice plate. 36, as illustrated in FIG. 4 of the drawings. As has been noted, the embodiments of FIGS. 2 and 6, for example, comprehend the use of multi-branched feeder passage-s, such .as the bifurcated feeder passage 35 there illustrated, whereby each component orifice slot 40 may be selectively supplied with the'retofore discrete streams of polymers, which polymers may differ as to physical characteristics. Of course, a non-conjugated filament of the desired cross-sectional configuration may be produced by the embodiments of FIGS. 2 and 6 simply by supplying the identical spinnable medium to all feeder branches, such as branches 34 and 42. Alternatively, a non-conjugated filament may be produced by employing orifice plates having formed therein unbranched feeder passages 48 supplying each component spinneret orifice 40, as illustrated in FIG. 4. As in the embodiments of FIGS. 2 and 6, the orifice plates of FIG. 4 may be arranged in the desired sequences of two -or more plates, which sequences of plates may optionally be interposed by spacer or partition plates having distribution apertures so formed and arranged therein as to align with the upper regions of the unbranched feeder passages 48. With ;this arrangementof feeder passages,each composite spinneret orifice 20 will be totally supplied by a single spinnable medium. Obviously, any desired sequence or sequences of the orifice plates illustrated in FIG. 4, having unbranched feeder passages 48, may be combined with a sequence or sequences of orifice plates containing multibranched feeder passages, such as the bifurcated feeder passages 35 shown, for example, in the FIG. 2 embodiment.

It will be apparent that many widely varying embodiments and modifications are possible in the light of the above teachings and maybe made without departing from the spirit and scope thereof. It is, therefore, to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specically described herein and it is not to be otherwise limited.

What is claimed is:

1. A laminated spinneret for use in the production of filaments of diversifiorm cross-sectional configuration comprising the combination of a plurality of superposed, interchangeable orifice plates, each having vari-dimensional slot means formed along a common periphery and registrable with the slot means of adjacent orifice plates to thereby define a composite orifice slot means of variable cross-sectional configuration, said .orifice plates having at least one aperture formed therein and arranged to align with similar apertures of adjacent plates to thereby define at-least one distribution passage extending transversely of the planes of said plates, at least one feeder passage formed in each of said orifice plates and interconnecting said distribution passage with said slot means.

2. A laminated spinneret for use in the production of filaments of diversiform cross-sectional configuration comprising the combination of a plurality of superposed, interchangeable orifice plates, each having vari-dimensional slot means formed along a common periphery and registrable with the slot means of adjacent orifice plates to thereby define a composite orifice slot means of variable crosssectional configuration, each of said orifice plates having a plurality of spaced apertures arranged to align with similar apertures of adjacent plates to thereby define a plurality of distribution passages extending transversely of the planes of said plates, a plurality of feeder passages formed in each of said orifice plates, each of said feeder passages interconnecting at at least one of said plurality of distribution passages with said slot means.

3. A spinnerct as defined in claim 2 wherein each of said feeder passages is bifurcated to interconnect a se- 10 lected pair of said plurality of distribution passageways with each of said orifice slots.

References Cited by the Examiner 5 UNITED STATES PATENTS 2,031,387 2/36 Schwarz 18-8 3,017,686 1/621 Breen et a1. 18--8 0 WILLIAM J. STEPHENSON, Primary Examiner.

MICHAEL V. BRINDISI, Examiner. 

1. A LAMINATED SPINNERET FOR USE IN THE PRODUCTION OF FILAMENTS OF DIVERSIFORM CROSS-SECTIONAL CONFIGURATION COMPRISING THE COMBINATION OF A PLURALITY OF SUPERPOSED, INTERCHANGEABLE ORIFICE PLATES, EACH HAVING VARI-DIMENSIONAL SLOT MEANS FORMED ALONG A COMMON PERIPHERY AND REGISTRABLE WITH THE SLOT MEANS OF ADJACENT ORIFICE PLATES TO THEREBY DEFINE A COMPOSITE ORIFICE SLOT MEANS OF VARIABLE CROSS-SECTIONAL CONFIGURATION, SAID ORIFICE PLATES HAVING AT LEAST ONE APERTURE FORMED THEREIN AND ARRANGED TO ALIGN WITH SIMILAR APERTURES OF ADJACENT PLATES TO THEREBY DEFINE AT LEAST ONE DISTRIBUTION PASSAGE EXTENDING TRANSVERSELY OF THE PLANES OF SAID PLATES, AT LEAST ONE FEEDER PASSAGE FORMED IN EACH OF SAID ORIFICE PLATES AND INTERCONNECTING SAID DISTRIBUTION PASSAGE WITH SAID SLOT MEANS. 